


like a vandal

by nilchance



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Ecto-Genitalia (Undertale), M/M, Overstimulation, Plot What Plot/Porn Without Plot, Sibling Incest, Underfell Papyrus, Underfell Sans, facesitting
Language: English
Status: Completed
Published: 2017-04-14
Updated: 2017-04-14
Packaged: 2018-10-18 19:29:28
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,065
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10623603
Author URL: https://archiveofourown.org/users/nilchance/pseuds/nilchance
Summary: Whether Papyrus hits him with the belt or gets his junk out, Sans's day has gotten much more interesting.





	

**Author's Note:**

> Betaed by the most excellent Poisontaster, who doesn't even go here and deserves a purple heart for the friendship wars.

Sans wakes up when he hits the floor. Like usual, he comes up panicked and violent. A bone attack surges into his hand, but before he can throw it someone stomps on his wrist. The attack fizzles, because Sans knows the shit-kicking boot that's pinning him to the ground.

"Hey, boss," Sans says with his best placating smile.

Papyrus towers over him, not looking very placated. He's in an ideal position to kick Sans in the ribs. Nice of him to block out the kitchen's overhead lights with his body, though. What a dollface.

"You were sleeping." Papyrus does love to state the obvious. " _Again_. Despite my repeated, explicit warnings not to leave the house completely unguarded."

There's no chair under Sans. He must’ve fallen asleep standing up again and Papyrus just shoved him over backwards. The endless joys of low HP. Wiggling his fingers, Sans says agreeably, "Can't really argue with that."

Papyrus glowers. Then he huffs a sigh and starts to unfasten his belt.

Well then. Whether Papyrus hits him with the belt or gets his junk out, Sans's day has gotten much more interesting. Now that he looks, he can see the blush high on Papyrus's cheekbones. Hear the way Papyrus is breathing slow and even, like the moment before he throws a ranged attack. If Sans touches his leg, he bets that the bone would be hot to the touch.

"Stop leering," Papyrus snaps, and releases Sans's wrist in order to take off his boots. His pants hit the floor a second later. He's already got a pussy, magic ready to go, and he's slick. There are smears of red on the inside of his femurs.

His smolder is somewhat dented by the fact that he stops to fold his pants like a total nerd.

"You know I'm always up for some afternoon delight." Sans mimes jerking off, in case the pun was too subtle.

With a disgusted noise, Papyrus kneels. He manages to put fuck-you swagger into going to his knees, like Sans might get ideas about who's in charge here.

Ha. Papyrus never quite gets that Sans wouldn't take charge if the world was ending. Too lazy. Too useless. Fuck the world anyway.

Then again, the world has its upsides right now, and there are definitely other things Sans would like to fuck.

Papyrus straddles Sans's face, close enough that Sans's mouth waters, far enough that Sans can't reach him if he sticks his tongue out.

"Yeah, this ain't helping with the leering," Sans says, hoarse. His own magic has surged up between his hips, aimless and shapeless until he knows what Papyrus wants. He puts his hand on Papyrus's leg and yeah, the bones radiate warmth like Papyrus has been training in Hotland for hours.

Whipcrack fast, Papyrus grabs him by the wrist and pins his hand to the floor again. His voice scrapes across Sans's bones like the edge of a knife. "Did I tell you to put your filthy hands on me?"

The new position puts Papyrus's cunt even closer. Shuddering, Sans meets Papyrus's murderous glare. "No, boss."

"Pathetic. Lucky for you, the great and terrible Papyrus is feeling merciful." Papyrus strokes his thumb over the inside of Sans's wrist. "Open your mouth and stick out your tongue."

Burning, Sans does. He happens to graze the underside of Papyrus's clit, and that quick taste makes him groan. Papyrus jerks against him, fingers digging into the hollow between radius and ulna. Then he presses his cunt down and grinds, slow, rubbing himself off against Sans's tongue.

The world narrows down to a pinpoint. There is only Papyrus around him, above him, taste and scent and sound and sight. Papyrus is staring him down, devouring every reaction Sans has. Sans can't exactly breathe, dizzy with the lack of air. He's just something for Papyrus to use to bring himself off, just a mouth to ride, and knowing that drags the last bit of fight from his bones. He relaxes so much he could sink through the floor.

The precise rhythm of Papyrus's hips stutters. His breathing is getting ragged, his eyes more bleary as Sans watches. His iron control is wavering. Sans almost never gets to see Papyrus like this, a heady rush of power even though he's the one getting fucked.

Papyrus grinds down into his mouth rougher, quicker, and Sans moans to fuzzily indicate that he is totally down with this new development. It comes out muffled, obscenely wet, more vibration than noise.

Papyrus hisses "yes, fuck," like he's being scalded, eyes closing. His clit is swelling against Sans's tongue as he gets closer and closer to coming, his wetness trickling down Sans's jaw now. More deliberately, Sans growls so Papyrus can feel it.

With a last hitch of breath, a vulnerable little noise that wraps around Sans's spine like a fist, Papyrus comes. He comes hard and silent, curling in on himself. It's not like sucking dick, there's no spurt of come to swallow, but there is another long pulse of wetness to spill onto Sans's eager tongue and run down his throat.

Maybe this is supposed to be a punishment, since Papyrus is so pissy at him, but Sans can't keep back his grateful, gut-deep moan. He's messed up and Papyrus hasn't even touched him below the collarbones.

Papyrus takes a deep breath and recovers himself. He gets one look at Sans's face and his expression goes dangerously smug. Sometimes Papyrus has trouble with reading people, but he's never had much trouble reading _Sans_. Especially when it comes to fucking, Papyrus figured Sans out a long time ago.

“Well,” Papyrus says. "There's at least one reason not to kill you."

Too abruptly, Papyrus climbs off him. Sans's face is bare and he hasn't got the right smile on at all, his mask ripped off and flung away. The open air feels cold on his mouth, chin and cheeks where Papyrus drenched him. Papyrus studies his handiwork with a critical eye, then runs his thumb over Sans's teeth.

"Look at you." Papyrus says. "You're a mess. Perhaps I should leave you to--"

Sans drags Papyrus's thumb into his mouth and sucks hard. The leather glove tastes like a thousand other nights like this one, like a bell to Pavlov's dog, spit welling up in Sans's mouth.

Slowly, eyes hooded, Papyrus gives Sans his index finger to suck on, too.  He glances at Sans's pelvis, his magic still shapeless but blazing with heat. Then he thrusts his fingers shallowly into Sans's mouth, dragging across the palate until Sans gags a little.

"Really, brother," Papyrus sighs, like he's not smirking and his pussy isn't still soaked. "Have a little dignity."

Sans manages not to bite him. Some of his annoyance must show on his face, because Papyrus snorts and adds a third finger. Sans's jaw aches, a dull pain that's getting sharper with every second. He pants around Papyrus's fingers, his fingers dragging on their shitty linoleum floor. Good thing they're in the kitchen, because there's going to be a mess.

"Please," Sans says, or tries to say. It's about as articulate as one could expect. He hates begging, and it's twice as humiliating because it gets him hot. Three times as humiliating because Papyrus knows it and grins meanly whenever he cracks.

"Don't talk with your mouth full." Papyrus pulls his fingers out. Coughing, Sans goes to wipe at the spit he's added to the slip-and-slide Papyrus made of his face. Papyrus says, low, "No. Leave it."

Sans drops his arm like a puppet with his strings cut.

Papyrus's smirk gets wider, satisfied. "Now what were you saying? I couldn't make it out."

Fucker. Sans drags a ragged gasp into his lungs and says through his teeth, "Please."

"I can hardly help you if you won't be _specific_." Papyrus curls his fingers around Sans's lower vertebrae and squeezes. Papyrus could crush him, cripple him, dust him. Sans whines and opens his legs wider. "Please what?"

Sans hates him. Sans loves this. "Please tell me what to do."

That's the right thing to say. Grip tightening, claustrophobic, Papyrus takes a breath. His voice is steady again when he says, "I suppose I have to do everything around here. Jerk yourself off."

Sans's magic snaps into the shape of a dick so fast that it aches. It's hilarious, and Sans is snickering a little even as he's taking himself in hand. The first touch brings a blurt of precome over his fingers, and his hips hitch forward into it.

"I've barely touched you." Papyrus leans over Sans to peer into his face, eating his reactions. "But you're even wetter than I am."

Sans shudders. His eyes close to get away from that deep, uncomfortable stare, but at the warning prickle of claws against his vertebrae make them snap open again. "Yeah. You got me all messed up, boss."

"Of course I do." There's no bite in the words. They're simple fact. "I own you."

"Yeah, you do," Sans breathes. He's been close since Papyrus sat on his face, and every stroke of his hand sharpens the need in his gut. It’s too easy. He's braced for Papyrus to stop him, to drag his hand away, to hit him, but Papyrus doesn't move. Only watches. "Fffuck, I'm gonna..."

"Good," Papyrus says, and leans down to take Sans's dick in his mouth.

It's like he skips straight past Sans's brain to kick off the emergency brake on his junk. Mindlessly, stupidly, Sans arches into Papyrus's mouth and Papyrus shoves him flat again. That little spark of pain and the rare shock of Papyrus sucking him off is enough. Sans comes, his voice ringing off the walls.

Papyrus doesn't spit or bite. He swallows. When he pulls back, it's only to frame Sans's dick between his fingers and lick him clean. He doesn't stop, even when Sans starts to struggle to get away.

"Holy fuck," Sans says, voice climbing higher with every word. "Fucking-- shit, _fuck_ \--"

He's still oversensitive, and each slow drag of Papyrus's tongue is a bright silver flashbulb of _too much_. His leg is jerking, until Papyrus pins that too, holding Sans open to better lick him clean.

Sans grabs at his own skull, digging his fingers in because he needs something to grip. Papyrus doesn't stop him, but he also doesn't let up. There's red slick smeared across his teeth and tongue.

"I'm," Sans manages. Then words give way to short, hurt whimpering. He's shaking all over, violent. There's gonna be bruises on his tailbone where Papyrus is grinding him into the floor. "Can't--!"

And then he can, because he is.

It doesn't feel like an orgasm, more like a back alley stabbing, but he spills a second, weaker spurt of come into Papyrus's mouth. For a terrifying moment, it seems like Papyrus might keep going, and Sans's body is gathering up to fight Papyrus the fuck _off_ of him when Papyrus just lets him drop to the floor. 

Fastidious as a cat, Papyrus licks his teeth clean and checks if his scarf is askew. Sans pants and tries to figure out if he's dying.

"It's not up to you whether you can or can't," Papyrus says.

"Hnngh." Did Sans jizz out his fucking spinal fluid? Marrow? It feels like he damaged something. "S'rry."

Papyrus picks up his pants. "For instance, I believe you can get off your lazy tailbone and clean up this floor before I get back from my shower."

"Boss," Sans whines.

Papyrus raises a fist, idly, and Sans shuts up.

As if he was never interrupted, Papyrus touches the back of his knuckles to Sans's hot face. His gentleness is more terrifying than any threat could be. "I believe in you, brother. And if you fail me, I believe that I will make you very, very sorry."

Papyrus walks away. The distant sound of his humming carries as he goes up the stairs. 

Without him, the kitchen feels smaller and very cold.

Sans is still shivering with aftershocks. The clatter of his bones mixes with the house's pipes rattling as the shower kicks on.

Slowly, Sans grins. If he tries, maybe he can get a quick nap in before Papyrus comes back to find him just like this.

He’s always sorry. It’s nice to have a reason for it once in a while.

**Author's Note:**

> "I got your name  
> Hanging from my chain  
> Don’t you wanna claim  
> My body like a vandal?"  
> \- Natalia Kills, Problem


End file.
